Question

Assume that you have an ArrayList variable named a containing 4 elements, and an object named element that is the correct type to be stored in the ArrayList.

Which of these statements adds the object to the end of the collection?1. a[3] = element;
2. a.add(element;
3. a[4] = element;
4. a.add(element);

Answer 1

Answer:

Option (4) is the correct answer.

Explanation:

In Java programming language ,array collection starts from 0 index location and ends in a size-1 index location. So to access the last elements the user needs to use a[Size-1] statement. so to modify the value of the last location of the array the user needs to use "a[size-1]= element;".

But when the user wants to add some new value to the end of the array list collection then he needs to use the statement--

a.add(element); //where add is a function, element is a value and a is a array list object.

Another option is invalid because--

• Option 1 is not the correct because "a[3]=element;" modify the value of the 3rd element of the array.
• Option 2 gives a compile-time error because add functions bracts are not closed.
• Option 3 gives the error because a[4] gives the location of the 5th element of the array but the above question says that a is defined with 4 elements.